// Copyright 2013 The Chromium Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

#ifndef NET_DNS_MDNS_CLIENT_H_
#define NET_DNS_MDNS_CLIENT_H_

#include <stdint.h>

#include <memory>
#include <string>
#include <vector>

#include "base/callback.h"
#include "net/base/ip_endpoint.h"
#include "net/dns/dns_query.h"
#include "net/dns/dns_response.h"
#include "net/dns/record_parsed.h"

namespace net {

class DatagramServerSocket;
class RecordParsed;

// Represents a one-time record lookup. A transaction takes one
// associated callback (see |MDnsClient::CreateTransaction|) and calls it
// whenever a matching record has been found, either from the cache or
// by querying the network (it may choose to query either or both based on its
// creation flags, see MDnsTransactionFlags). Network-based transactions will
// time out after a reasonable number of seconds.
class NET_EXPORT MDnsTransaction {
public:
    // Used to signify what type of result the transaction has received.
    enum Result {
        // Passed whenever a record is found.
        RESULT_RECORD,
        // The transaction is done. Applies to non-single-valued transactions. Is
        // called when the transaction has finished (this is the last call to the
        // callback).
        RESULT_DONE,
        // No results have been found. Applies to single-valued transactions. Is
        // called when the transaction has finished without finding any results.
        // For transactions that use the network, this happens when a timeout
        // occurs, for transactions that are cache-only, this happens when no
        // results are in the cache.
        RESULT_NO_RESULTS,
        // Called when an NSec record is read for this transaction's
        // query. This means there cannot possibly be a record of the type
        // and name for this transaction.
        RESULT_NSEC
    };

    // Used when creating an MDnsTransaction.
    enum Flags {
        // Transaction should return only one result, and stop listening after it.
        // Note that single result transactions will signal when their timeout is
        // reached, whereas multi-result transactions will not.
        SINGLE_RESULT = 1 << 0,
        // Query the cache or the network. May both be used. One must be present.
        QUERY_CACHE = 1 << 1,
        QUERY_NETWORK = 1 << 2,
        // TODO(noamsml): Add flag for flushing cache when feature is implemented
        // Mask of all possible flags on MDnsTransaction.
        FLAG_MASK = (1 << 3) - 1,
    };

    typedef base::Callback<void(Result, const RecordParsed*)>
        ResultCallback;

    // Destroying the transaction cancels it.
    virtual ~MDnsTransaction() { }

    // Start the transaction. Return true on success. Cache-based transactions
    // will execute the callback synchronously.
    virtual bool Start() = 0;

    // Get the host or service name for the transaction.
    virtual const std::string& GetName() const = 0;

    // Get the type for this transaction (SRV, TXT, A, AAA, etc)
    virtual uint16_t GetType() const = 0;
};

// A listener listens for updates regarding a specific record or set of records.
// Created by the MDnsClient (see |MDnsClient::CreateListener|) and used to keep
// track of listeners.
class NET_EXPORT MDnsListener {
public:
    // Used in the MDnsListener delegate to signify what type of change has been
    // made to a record.
    enum UpdateType {
        RECORD_ADDED,
        RECORD_CHANGED,
        RECORD_REMOVED
    };

    class Delegate {
    public:
        virtual ~Delegate() { }

        // Called when a record is added, removed or updated.
        virtual void OnRecordUpdate(UpdateType update,
            const RecordParsed* record)
            = 0;

        // Called when a record is marked nonexistent by an NSEC record.
        virtual void OnNsecRecord(const std::string& name, unsigned type) = 0;

        // Called when the cache is purged (due, for example, ot the network
        // disconnecting).
        virtual void OnCachePurged() = 0;
    };

    // Destroying the listener stops listening.
    virtual ~MDnsListener() { }

    // Start the listener. Return true on success.
    virtual bool Start() = 0;

    // Actively refresh any received records.
    virtual void SetActiveRefresh(bool active_refresh) = 0;

    // Get the host or service name for this query.
    // Return an empty string for no name.
    virtual const std::string& GetName() const = 0;

    // Get the type for this query (SRV, TXT, A, AAA, etc)
    virtual uint16_t GetType() const = 0;
};

// Creates bound datagram sockets ready to use by MDnsClient.
class NET_EXPORT MDnsSocketFactory {
public:
    virtual ~MDnsSocketFactory() { }
    virtual void CreateSockets(
        std::vector<std::unique_ptr<DatagramServerSocket>>* sockets)
        = 0;

    static std::unique_ptr<MDnsSocketFactory> CreateDefault();
};

// Listens for Multicast DNS on the local network. You can access information
// regarding multicast DNS either by creating an |MDnsListener| to be notified
// of new records, or by creating an |MDnsTransaction| to look up the value of a
// specific records. When all listeners and active transactions are destroyed,
// the client stops listening on the network and destroys the cache.
class NET_EXPORT MDnsClient {
public:
    virtual ~MDnsClient() { }

    // Create listener object for RRType |rrtype| and name |name|.
    virtual std::unique_ptr<MDnsListener> CreateListener(
        uint16_t rrtype,
        const std::string& name,
        MDnsListener::Delegate* delegate)
        = 0;

    // Create a transaction that can be used to query either the MDns cache, the
    // network, or both for records of type |rrtype| and name |name|. |flags| is
    // defined by MDnsTransactionFlags.
    virtual std::unique_ptr<MDnsTransaction> CreateTransaction(
        uint16_t rrtype,
        const std::string& name,
        int flags,
        const MDnsTransaction::ResultCallback& callback)
        = 0;

    virtual bool StartListening(MDnsSocketFactory* factory) = 0;

    // Do not call this inside callbacks from related MDnsListener and
    // MDnsTransaction objects.
    virtual void StopListening() = 0;
    virtual bool IsListening() const = 0;

    // Create the default MDnsClient
    static std::unique_ptr<MDnsClient> CreateDefault();
};

NET_EXPORT IPEndPoint GetMDnsIPEndPoint(AddressFamily address_family);

typedef std::vector<std::pair<uint32_t, AddressFamily>>
    InterfaceIndexFamilyList;
// Returns pairs of interface and address family to bind. Current
// implementation returns unique list of all available interfaces.
NET_EXPORT InterfaceIndexFamilyList GetMDnsInterfacesToBind();

// Create sockets, binds socket to MDns endpoint, and sets multicast interface
// and joins multicast group on for |interface_index|.
// Returns NULL if failed.
NET_EXPORT std::unique_ptr<DatagramServerSocket> CreateAndBindMDnsSocket(
    AddressFamily address_family,
    uint32_t interface_index);

} // namespace net

#endif // NET_DNS_MDNS_CLIENT_H_
